Variable speed transmission



Sept. 7, 1937.

C. H. OSLUND VARIABLE SPEED TRANSMISSION 2 Sheets-Sheet 1 Filed Nov. 20, 1934 Sept. 7, 1937. c. H. osLuND VARIABLE SPEED TRANSMISSION Filed Nov. 20, 1934 2 Sheets-Sheet 2 Ln Z Patented Sept. 7, 1937 UNITED STAT-ES PATENT OFFICE.

2,09%469 VARIABLE SPEED TRANSMISSION Charles H. oslund, Worcester, Mass. Application November 20,1934, Serial No. 753,949 1 Claim. (01. 74-29017) This invention relates to variable speedtrans- Fig. 5 is a detail showing the contour of the missions, and more particularly to transmissions cam on the variable cone; of the type having pulleys connected by an endless Fig. 6 is an end view of the flanged, hub with belt, one of the pulleys being of the expansible the cam rollers mounted therein; 5 type so that its pitch diameter will vary as the Fig. 7 is an elevation, partially broken away,

distance between the pulley centers is adjusted. showing the relationship of the various parts. In priortransmissions of this type it has been when adjusted for minimum speed; and. thepract ice toform the expansible pulley from, Fig. 8 is a view similar to Fig. 7 showing the a pair of opposed cones which are relatively mov parts adjusted for maximum speed. 10 able in an axial direction, and to employ a spring The embodiment illustrated comprises a pair 10 to urge one cone toward the other and thus grip of opposed cones Ill and II revoluble about a comthe belt: between the cones. Such constructions mon axis and forming a pulley. A'second pulley are bulky and expensive. Moreover, the spring I2 is 'revoluble about an axis spaced from the first must be strong enough to ensure the required axis, and 'anendless belt M, which is preferably gripping action under all conditions of adjustof the V-type, connects the two pulleys. The pul- 15 ment, and since the spring loading will vary with ley ['2 is shown fixed to the shaft l5 of an electric and depends solely upon the cone position regardmotor l6, and the cones lll and II are shown less of the rate of power transmission, it neces mounted on a shaft l8 parallelto the motor shaft. sarily follows that under many conditions of A pinion I9 is fixed to the shaft l8, and this pin- 0 operation the pressure upon the belt and the reion meshes with a gear which may serve to 20 sultant wear are very much greater than necesactuate any desired apparatus. sary. In order that the speed of the driven shaft l8 It is accordingly one object of the invention to may be controlled, I provide means for varying provide a variable speed transmission which will the pitch diameter of the pulley Ill-l I, this varibe simple, compact, and comparatively inexpen ation being efi'ected automatically in response sive to manufacture. to an adjustment in the distance between the It is a further object of the invention to proaxes of the pulleys. For this purpose the two vide a variable speed transmission so constructed cones l0 and II are made relatively movable in and arranged as to avoid excessive wear upon the an axial direction. In the preferred construction driving belt. illustrated, the cone I0 is formed with an integral 30 It is a-further object of the invention to provide hub 22 which is fixed to the shaft l8 by means a variable speodtransmis'sion so constructed and of a set-screw 23, and the cone II is arranged for arranged that the belt will be gripped only hard axial sliding movement along the shaft. enough to avoid slippage under the particular The desired adjustment in the distance between conditions prevailing at the time. the pulley axes'is preferably effected by bodily It is a further object of the invention to promoving the motor iii. For this purpose the motor vide a variable speed transmission which will be is shown mounted on a base plate'25 which is capable of transmitting a predetermined maxihinged at one end to a frame 26 by means of a mum power irrespective of adjustments in the pin 2'! parallel to the motor shaft. The other 40 Speed ratiO- end of the base plate is connected to the frame 40 With these and other objects in view, as will by means of a threaded rod 29 which is held in be apparent to those skilled in the art, the invena desired position of longitudinal adjustment by tion resides in the combination of parts set forth means of two manually operable nuts 30. r in the specification and covered by the claim aD- The various parts are so arranged that whatr pended hereto. ever may be'the adjustment of the center dis- Referring to the drawings illustrating one emtance between the shafts, and the resultant bodiment of the invention and in which like refspeed ratio, the driving tension of the belt I! will erence numerals indicate like parts, serve to move the cone II toward the cone l0 Fig, 1 is an elevation of a variable speed transand thus grip the belt between the cones. For r 0 mission, certain parts being broken away for this purpose, the cone-H is made movable relaclearness of illustration; tive to the shaft l8 both axially and rotatably, Fig; 2 is an end elevation of the mechanism and cooperating parts are provided which will shown in Fig. 1; move the cone axially in response to a relative Fig. 3 is a section on the line 3-3 of Fig. 7; rotative movement. In the preferred construc- Fig. 4 is an elevation of the movable cone; tion, this axial movement is brought about through the means of cooperating cam devices fixed to the shaft and to the movable cone respectively. The illustrated embodiment for effecting the desired result comprises a hub 32 5 fixed to the shaft I8 adjacent to the movable cone H by means of a set-screw 33. This hub is provided with an integral annular flange 34 which projects toward the movable cone in spaced relation with the shaft. Two pins 36 10 project substantially radially inward from the flange 34, and on these pins are mounted rollers 3! which engage cams 38 projecting from the movable cone. The pins 36, as well as the cams 38, are located 180 degrees apart and hence are symmetrically disposed about the axis of the shaft. Moreover, each cam 38 ispreferably symmetrical with respect to an axial plane, as shown particularly in Fig. 5. As a result of this construction, the pulleys may be rotated in either direction, and an increase in the driving tension of the belt will always turn the movable cone relative to the shaft and thus efiect an axial movement of this cone toward the fixed cone.

In the preferred construction illustrated, I have shown a comparatively light spring 40 to bias the movable cone toward the fixed cone. This spring is of the compression type, and surrounds the shaft l8 between the hub 32 and the movable cone. The spring 40 ensures a light contact between the movable cone and the belt even under stationary conditions and takes up any lost motion which would otherwise be present. -The operation of the invention will now be 55 apparent from the above disclosure. When the motor is started it will rotate the pulley l2 and drive the belt I. This will immediately turn the movable cone H about the shaft l8, and the cams 38 will engage the rollers 31, thus crowding the movable cone axially toward the fixed cone l0 and gripping the belt between the cones. The cones I0 and II and the shaft l8 will then rotate as a unit. An increase in the load imposed by the driven machine will cause the driving tension of the belt to increase, which will result in a firmer gripping of the belt. The pitch diameter of the pulley l0-,-ll can be varied by adjusting the center distance between the shafts through the medium of the nuts 30, and in this way the speed of the shaft 18 can be controlled as desired. Since the diameter of the driving pulley I2 is fixed, the belt will travel at a constant speed irrespective of adjustments in the speed ratio. This makes it possible to utilize the full power of the motor, whether the driven machine is operated at a slow speed or a high speed.

It will be seen that the belt will be gripped no tighter than is necessary to transmit the power imposed at the time by the driven machine. Hence the wear on the belt will be greatly reduced, The cam mechanism is enclosed and protected by the annular flange 34. The entire construction is simple, compact and inexpensive.

In the specification, the parts I0 and H are described as cones. This term is intended to be given a broad interpretation, since it is obviously unnecessary that these parts be cones in the strictly mathematical sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

A variable speed transmission comprising a rotatable shaft, a pair of opposed cones mounted on the shaft and forming a pulley, one of said cones being movable relative to the shaft both axially and rotatably, an endless belt engaging the cones, a hub fixed to the shaft adjacent to the movable cone, an annular flange on the hub and projecting toward the movable cone, a pin projecting substantially radially inward from the flange, a roller on the pin, and a cam projecting from the movable cone into engagement with the roller, said cam and roller cooperating to move the movable cone axially toward the other cone whenever it is moved rotatably relative to the shaft under the influence of the driving tension of the belt, the flange serving as a protective enclosure for the cam and roller.

CHARLES H. OSLUND. 

